Katsarosite

Chemical formula: Zn²⁺(C₂)⁶⁺O₄·₂H₂O

Katsarosite is a hydrated zinc oxalate, a rare secondary mineral with a white or yellow color, occurring in the oxidation zones of ore deposits.

## Characteristics Katsarosite is a hydrated zinc oxalate, belonging to the humboldtine group. It forms aggregates of very fine, platy or acicular crystals, rarely exceeding 50 micrometers in length. It typically occurs as coatings, crusts, and earthy or powdery aggregates on host rocks. Due to the small size of its crystals, its macroscopic features are difficult to observe without magnification. ## Physical Properties This mineral is very soft, with a Mohs hardness of only 1.5-2, meaning it can be scratched with a fingernail. It has a dull to earthy luster. It is a light mineral. The crystals are flexible. ## Colors and Varieties Katsarosite occurs in colors ranging from pure white to yellow. White color characterizes specimens with low iron content, while a yellow hue indicates the presence of iron impurities. ## History and Name The mineral's name comes from the Greek word "κατσάρος" (katsaros), meaning "curly" or "tangled," which alludes to the typical form of its crystal aggregates. It was approved as a new mineral by the IMA in 2017. The type locality (discovery site) is the Esperanza mine in Lavrio, Greece. ## Uses Katsarosite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and for scientists.

Properties

Mohs hardness: 1.5-2
Luster: Earthy
Cleavage: on {110}
Fracture: Irregular/Uneven
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of katsarosite with the naked eye is practically impossible and requires laboratory analysis (e.g., XRD, EDS). Preliminary identification can be based on its occurrence as white or yellow, earthy or powdery coatings in the oxidation zones of zinc deposits, in association with other secondary minerals. Its extreme softness is also a characteristic feature. ## Distinguishing from Similar Minerals It can be confused with other secondary zinc minerals of similar appearance, such as hydrozincite, which, however, reacts with hydrochloric acid. Gypsum, which is slightly harder (2 on the Mohs scale), can also have a similar appearance. Final differentiation requires specialized tests. ## Crystal Forms Katsarosite forms very small, platy or acicular crystals that combine into tangled, woolly, or felt-like aggregates. It also occurs as earthy aggregates and powdery coatings.

Geological environment

## Genesis Katsarosite is a secondary mineral, formed in the oxidation zones of zinc-rich ore deposits. Its genesis is related to the interaction of oxalic acid-containing solutions with zinc minerals, such as sphalerite. Oxalic acid can originate from the decomposition of organic matter or the activity of microorganisms, such as lichens growing on rocks. ## Mineral Associations At its type locality in Greece, katsarosite co-occurs with gypsum, sphalerite, pyrite, quartz, calcite, annabergite, and goethite. ## Localities The most important and best-documented occurrence is its type locality – the Esperanza mine in the Kaminiza mine complex, in the Lavrio (Laurion) region of Greece.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a katsarosite specimen primarily depends on the richness and purity of the coating on the rock matrix. Most valued are specimens where the mineral forms distinct, dense aggregates of intense, pure white or uniformly yellow color. The aesthetics of the host rock and the presence of well-defined associated minerals are also important. ## Popular Localities The only source of collectible specimens is currently the historic mining region of Lavrio in Greece, from where all known samples of this mineral originate.

Care and storage

## Cleaning Katsarosite specimens are extremely delicate and sensitive. Mechanical cleaning and contact with water, which can dissolve or damage the fine crystals, should be avoided. If cleaning is absolutely necessary, a stream of compressed air can be carefully used from a safe distance. ## What to Avoid All chemicals, acids, detergents, and solvents. Contact with water, high humidity, and temperature changes should be avoided. The mineral is very soft, so it must be protected from any abrasion or impact. ## Storage It is recommended to store specimens exclusively in sealed, lidded "micromount" boxes, away from dust, humidity, and direct light. It is best displayed under glass or in specialized display cases to minimize the risk of damage.